How to determine gauge of winding wire

Thread Starter


Joined Jan 21, 2018
I want to rewind a motor but do not have a means to measure the gage of the existing wire. Is there any way to determine the gage? I only have foot-rule


Joined Jul 18, 2013
You really need a digital micrometer, also you need to remove the enamel for accuracy.
Cut off a small piece and take into either a rewind shop or a local engineering shop, they should measure it for a favour.


Joined Sep 17, 2013
Welcome to AAC!
If all you have is a 1 foot rule, here's a way :-
1) Cut off a 6" length of the wire (not critical),
2) Bend the wire into an 'L' shape,
3) Mark off a 1" line on a piece of card,
4) Place one leg of the L, to act as an axle, at one end of the 1" mark,
5) Roll the 'axle' along the mark, the other leg acting as an indicator (clock hand).
6) Count the number n of rotations to reach the other end of the mark.
7) Do the maths. Wire diameter d = 1"/(n*π*).

The answer won't be as accurate as Max's method, but should get you close to the nearest standard wire gauge size.

Beau Schwabe

Joined Nov 7, 2019
Another method is to wind the wire onto something as tight (close together) as you can and scan it with a flat bed scanner.... noting the DPI resolution of your scanner, count the number of turns and number of pixels to determine a relatively accurate diameter of the wire. Once you know the diameter of the wire you should be able to determine the gauge.


Joined Oct 2, 2009
Compare it visually with something you have at hand.
For example,
¼W thru hole resistor leads are about 0.58mm (23AWG)
½W thru hole resistor leads are about 0.67mm (22AWG)


Joined Oct 2, 2009
Try winding about 20-100 turns with turns very tightly together on a hollow tube and measure length of coil divided by number of turns.


Joined Mar 10, 2019
Why mess around when you can get it for $10.00 ??

Also if getting to such as rewinding it will probably come in handy in the future for many reasons.
That is ok for general use, but with a measuring error of +/- 0.2mm it is hard to measure fine wires with that device. There are more accurate digital calipers out there. I have one that is all metal, and resolution and error is 10 times better. I also have one like you posted, but use it for general measurements only.
Similar to: